U4-4847 Refactor ContentService (#1266)

* U4-4748 - refactor Content-, Media- and MemberTypeRepository

* Cleanup Attempt

* Cleanup OperationStatus

* U4-4748 - refactor Content-, Media- and MemberTypeService

* U4-4748 - cleanup locking

* U4-4748 - refactor Content-, Media- and MemberRepository

* U4-4748 - refactor ContentService (in progress)

* U4-4748 - all unit of work must be completed

* U4-4748 - refactor locks, fix tests

* U4-4748 - deal with fixmes

* U4-4748 - lock table migration

* Update UmbracoVersion

* Fix AuthorizeUpgrade

* U4-4748 - cleanup+bugfix lock objects

* U4-4748 - bugfix

* updates a string interpolation

src/Umbraco.Core/Services/MemberGroupService.cs

@@ -42,7 +42,9 @@ namespace Umbraco.Core.Services
             using (var uow = UowProvider.CreateUnitOfWork())
             {
                 var repository = uow.CreateRepository<IMemberGroupRepository>();
-                return repository.GetAll();
+                var groups = repository.GetAll();
+                uow.Complete();
+                return groups;
             }
         }
 
@@ -51,7 +53,9 @@ namespace Umbraco.Core.Services
             using (var uow = UowProvider.CreateUnitOfWork())
             {
                 var repository = uow.CreateRepository<IMemberGroupRepository>();
-                return repository.Get(id);
+                var group = repository.Get(id);
+                uow.Complete();
+                return group;
             }
         }
 
@@ -60,7 +64,9 @@ namespace Umbraco.Core.Services
             using (var uow = UowProvider.CreateUnitOfWork())
             {
                 var repository = uow.CreateRepository<IMemberGroupRepository>();
-                return repository.GetByName(name);
+                var group = repository.GetByName(name);
+                uow.Complete();
+                return group;
             }
         }